A spokesman for Israel’s Foreign Affairs Ministry blamed the European Union for financing the indoctrination of Palestinian children in the antisemitism at the heart of Hamas’ massacre of hundreds of Israeli civilians.

Hundreds of Hamas terrorists, reportedly with backing from Iran, invaded Israel from Gaza on Saturday morning, killing at least 900 Israelis and wounding thousands more. Hamas terrorists are holding an estimated 150 more Israelis as captives in the Gaza Strip. Images and videos that surfaced online from the attack depict Hamas militants murdering and mutilating the bodies of civilians.

A spokesman for Israel’s Foreign Affairs Ministry said European accommodation of rampant anti-Semitism in Palestinian communities in Gaza fostered the dehumanization of Israelis.

“The European Union was financing textbooks of the Palestinian authorities that were full of antisemitism and incitement for violence and terrorism against Jews,” spokesman Lior Haiat said Monday, according to The Washington Examiner. “Those textbooks are the root of the Palestinian terror against Israelis. Young people are being taught, educated, to hate Jews and to murder Jews.”

Israeli Prime Minister Benjamin Netanyahu has promised an unprecedented military campaign against Hamas in response to the attack, which has been called the worst day for Jews since the Holocaust.

“To my mind, not since the Holocaust have so many Jews been killed on one day,” Israeli President Isaac Herzog said. “And not since the Holocaust have we witnessed scenes of Jewish women and children, grandparents, even Holocaust survivors, being herded into trucks and taken into captivity.”

The Israeli military is preparing for a “complete siege” of Gaza, according to Israeli Defense Minister Yoav Gallant. Over the past few days, Israel’s air force has conducted bombing runs that hit locations key to Hamas’ military operation. The Israeli government has directed civilians living in Gaza to flee the area or risk danger in the invasion.

“I have given an order – Gaza will be under complete siege,” Gallant said, according to CNN. “We are fighting barbarians and will respond accordingly.”

In response, Hamas has ordered Palestinians living in Gaza to shelter in their homes, a move that has been condemned as another attempt by the terror group to use civilians as human shields against Israeli bombing runs. Hamas has also threatened to execute hostages.

“We declare that we will respond to any targeting of our people who are safe in their homes without warning, with the execution of our civilian hostages, and we will broadcast it with audio and video,” Abu Obaida, the spokesman for Hamas’ Al-Qassam Brigades, said in a post on Telegram.

U.S. National Security Council spokesperson John Kirby said Iran is “complicit” in the Hamas attacks on Israel over the weekend, doubling down on remarks a fellow Biden administration official made earlier on Monday.

Kirby spoke to media outlets about U.S. talks with Israeli officials about the status of the now-11 dead Americans and an unknown number of hostages caught in Israel’s full-scale war against an Iranian-backed terrorist organization.

When asked by MSNBC if the U.S. had any intelligence about the Wall Street Journal’s report where Iran indicated it had direct support and planning with Hamas in the attack, Kirby said the Biden administration had not seen any evidence.

“That said, of course, Iran has long supported Hamas and other terrorist networks throughout the region with resources, capabilities training,” Kirby said. “And so in that regard, clearly, Iran is complicit here. But in terms of specific evidence on this, on these sets of attacks — no, we don’t have anything.”

Deputy National Security Adviser Jonathan Finer would not confirm the Journal’s report on Monday but noted that officials were investigating the allegation.

“I think what we can be quite clear about is that Iran is broadly complicit in these attacks for having supported Hamas going back decades, for having provided financial support, for having provided training, for having provided weapons to Hamas,” Finer told ABC News.

“What we don’t have is direct information that shows Iranian involvement in ordering or planning the attacks that took place over the last couple of days. It’s something that we’re going to keep looking at closely. By the way, this is something that the Israeli government has said as well; broad complicity but no evidence of direct support although it’s something we are going to continue to watch.”

Iran reportedly has given billions of dollars to Hamas and other Palestinian terror groups over the last few decades to support attacks against Israel, providing weapons, funding, and training. A spokesperson for the terrorist organization told the BBC that it received support from Iran and others, although he declined to say who else provided support.

The Biden administration “has strengthened and emboldened the regime in Iran,” said the foreign policy experts at the Foundation for Defense of Democracies (FDD), a nonprofit focusing on national security and foreign policy.

The administration has loosened sanctions on Iran as it seeks a nuclear deal, which it has failed to deliver, and the result has been Iran’s ability to sell millions of barrels of oil per day.

Biden greenlit a $10 billion transfer from Iraq to Iran in July, and in August, he approved the unfreezing of $6 billion in Iranian oil revenues.

Defenders of the Biden administration claim that the money did not go to terrorism, but Iranian President Ebrahim Raisi said Iran would spend it however it wanted to.

On Sunday, Secretary of State Antony Blinken said: “We have not yet seen evidence that Iran directed or was behind this particular attack, but there is certainly a long relationship.”

Lina Khatib, director of the SOAS Middle East Institute at the University of London, said: “An attack of such scope could only have happened after months of planning and would not have happened without coordination with Iran.”

“Hamas, like Hezbollah in Lebanon, does not singlehandedly make decisions to engage in war without prior explicit agreement from Iran,” Khatib added.

Ryan Saavedra and Hank Berrien contributed to this report.